To understand a country, it helps to know its schools. To grasp Mexico, MIT historian Tanalís Padilla believes, that means learning about its rural “normales,” teacher-training schools with outsized historical influence on the country’s politics. This might seem surprising. At its height, the system of rural normales consisted of only 35 such boarding schools, scattered in the countryside, populated by the children of peasants and indigenous residents. Yet these schools had been founded on the ideals of the Mexican Revolution of the 1910s, which promised justice for the poor, land…